Kowski



C. CHUDZIKOWSKI.

ELECTRIC MUSICAL INSTRUMENT.

APPLICATION FlLED MAY 29.1914.

Patented Nov. 18, 1919.

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C. CHUDZIKOWSKI.

ELECTRIC MUSICAL INSTRUMENT.

APPLICATION FILED MAY 29. I914. 1,322,229. Patented Nov. 18, 1919.

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C. CHUDZIKOWSKI.

ELECTRIC MUSICAL INSTRUMENT.

APPLICATION FILED MAY 29. I914. 1,322,229. Patented Nov. 18, 1919.

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ELECTRIC MUSICAL INSTRUMENT.

APPLICATION FILED MAY 29, 1914.

1,322,229. Patented Nov. 18, 1919.

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CHARLES. CHUDZIKOWSKI, 0F CAMBRIDGE, MASSACHUSETTS, ASSIGNOR T0 CHORAL-CELO COMPANY, OF BOSTQN, MASSACHUSETTS, A CQBPURATION 0F MAINE.

ELECTRIG MUSICAL INSTRUMENT.

Specification of letters Patent.

Patented Nov. 1 8, 191%.

Application filed May as, 1914-. Serial in. eerese.

To all whom it may concern: 3

' Be it known that l[, CHARLES Gnunzr- KOWSKI, a citizen of the UnitedStates, residing at Cambridge, in the county of Middlesex and State of.Massachusetts, have invented certain new and useful Improvements inbrating of the diaphragm is caused to give ofi a predetermined musicalnote which the resonator relieves of any extraneous sounds or overtones,and delivers as a pure and single tone.

The invention will be readily understood froin an inspection of theaccompanying drawings, in which Figure 1 is a sectional elevation of oneunit, showing diagrammatically the means-for controlling the vibrationsof the sonorous body, Fig. 2 is a bot tom plan view of the diaphragm andits supportmg ring, Fig. 3 is a top plan view of the same; Fig. '4 is avertical section taken on the line H in Fig. 2, Fig. 5 is a fragmentaryplan view of the diaphragm, showing how the ribs are sha ed at thecenter,

Fig. 6 ,is .afr'agmentary side elevation, Fig. 7 1s a central verticalsection taken on the line 7-7 in Fi .8, Fig. 8 is a bottom plan view ofamodi ed form of diaphragm, Fig.

9 is a bottom plan view of another modified formof the invention, andFig. 10 is a central vertical section of the same.

As illustrated in Figs. 1 to 6, inclusive, the sonorous body comprises adiaphragm which is secured to or suitably positioned in proximity. toone end of a resonator 10. The resonator comprises preferably acylindrical sheet-metal tube, having a main bodyportion of uniformcross-section, a tapering portion 12, and a reduced neck 14. By thisconstruction the length of tube required to give the proper resonance isreduced, yet the opening of the neck is suflicient to enable therequisite loudness and volume of tone to.

be emitted.

The resonators are of various lengths, .according to the tone to beproduced, and they are supported by a frame 16, preferably felted at 17,or supported in any other suitable manner, and they are held either in ahorizontal or a vertical position. Although I have shown cylindricalresonators with reduced opening at one end, I do not wish to confinemyself to this particular construe-,x

tion, as I may use resonators of any desirable shape, size, or material;even 1n-s'ome cases making the tubes of concrete and square incross-section; and l hold all this to be well within the province of myinvention.

As here shown, a sheet of flexible material 18, such as leather, orcloth which has preferably been rendered impervious to air, is clampedbetween a pair of rings 20, 21, sald rings being held together by screwsor bolts- 22. The ring 20 is preferably lL-shaped in cross-section, andits periphery is kept from contact with the interior of the tube 10 by arin of yielding material 24, such as felt, or the like, which acts as apacking to form a tight joint between said ring and tube, and also toprevent contact between the two metal surfaces, when the ringssupporting the diaphragm are inserted in the tube.

Mounted upon the sheet 18 is a disk 26, preferably of wood, which isstiffened by ribs 28, here shown as radially disposed and shaped attheir inner ends to form a tight joint one with another, said diskbeing. slightly less in diameter than the opposmg flange of the ring 20.By this construction the central portion of the diaphragm, and

in fact its entire area with the exception of of ribs 29, 31, therebeing four in the present instance, the ribs of each air being separatedfrom each other to orm a U- shaped crosssection of the ring at thispoint. A pair of strips or hands 30, 32, preferably of highly resilientmaterial of considerable tensile strength, as vanadium steel, arelocated at right angles each to the other. These bands span the ring 21,extending over the ribs 29, 31, and have their outer ends secured to theexterior of the rin 21 by screws 34. These bands cross eac other at thecenter of the ring, and are preferably riveted together at the center.

I do not wish to confine myself to the use of strips or hands as atensioning means, or to any particular method of straining the same, asI may use rods of various cross-sections and any suitable means forapplying tension thereto. In other words, any known and suitable meansof giving the necessary tension may be employed.

An armature 38, preferably in the form of a. disk of soft iron having acentral boss 40, preferably of non-magnetic material, is located betweenthe flexible sheet 18 and the bands 30, 32, and said boss is separatedfrom said bands by a felt washer 42. A bolt 44 passes through the centerof the disk 26, armature 38; boss 40, the bands 30, 32, and a feltwasher 36, and clamps them all together, said bolt having a' washer 46under its head, which engages the upper surfaces of the ribs 28 at theirinner ends. Thus the bands 30, 32 and the flexible diaphragm andstiffener are all secured together so that they will vibrate together. Abar 48 engages each band 30, 32 near its end, between the ribs 29, 31,and is clamped against said band by means of screws or bolts 50, whichare threaded into the ring 21 on opposite sides of each band. Thesebolts are adapted to vary the tension of the bands 30, 32, andconsequently the pitch of the note emitted by the diaphragm. Where thediaphragms are tuned to pitches so high that the strain on the fulllength bands'30, 32, would be excessive to bring them to pitch, Ipreferably shorten the effective vibrational length of the bands in anysuitable manner, as for example, by the insertion of posts or bridges33, one end of which is secured to the diaphragm and the other end ofwhich bears against the band.

Owing to the connection of the central portion of the diaphragm with thetensioned bands 30, 32 at their point of intersection, the diaphragm 18though it may be itself somewhat lightly stressed, can vibrate only inunison with the bands 30, 32, or to the extent determined by thecharacter and tension of said bands. By increasing the tension uponthese bands, the pitch of the tone produced by the diaphragm can beraised, While by lessening the tension it may be lowered,

and in this way proper tuning may be effected. The resonator beingproportioned as to its diameter, length, etc., with refer- .magnets 52,in the present instance composed of four coils mounted un a plate 54',which is adjustably supporte by the screws 55, 56, coiiperating with atruss 58 secured at its ends to the ring 21. By means of the screws 55,56 the positions of the poles 60 of the electromagnets are adjusted,both for proximity and parallelism, with relation to the disk orarmature 38, so that the latter shall not strike said poles during itsvibration by the electromagnets.

The coils of the electromagnets are connected together and by wires 62,64 to a contact member 66, and a brush 67, respectively. The means forintermittently energizing the electromagnets comprises a pulsationdevice comprising a uniformly rotated ring or disk 68, having alternateteeth and insulating material 70, engaged by the brush 67. The rotationof the disk 68 is suitably timed by the synchronizer 71, of any suitabletype such as is employed in the musical instrument known as theChoralcelo, which is shown and described more or less fully in U. S.Letters Patent No. 1,098,983 granted to M. L. Severy and G. B. Sinclair,and dated June 2nd, 1914, among numerous patents to said parties.

The contact-member 66 coiiperates with a brush 72 carried b a ke 74,like the ke of a piano, and said rush 2 is connected y a wire 75 to onepole of a current source 76, the other pole of said source beinconnected by a wire 78 to a brush 79, and t is brush is in enga ement.with a shaft 80, which carries the dlsk 68. The disk 68 is rotated at aconstant speed by the synchronizer 71, and .when the key 74 is depressedto cause the brush 72 to engage the contact-member 66,rpulsatory currentis transmitted to the electromagnets 52, the frequency of saidpulsations being deto the required pitch.

As illustrated in Figs. 7 and 8, the sonorous body comprises a diaphragm82, prefer 130 aeaaaae ably made of metal, although any other suitablematerial may be employed. The diaphragm or disk 82 is formed with aperiphdecreases gradually from the center to the main central area ofthe disk is precluded rim. But in some cases thediaphragm need not be auniform taper, but may be otherwise shaped for particular qualities oftone.

As shown, the disk is tapered on both sides or faces, that is, bothfaces of the disk are slightly conical, although one face of the dislr..;n nay be flat and the other face conical from the'center to the"rim. The cross-sectional shape of-the diaphragm is varied inaccordance/with the pitch of the tone which it isdesired shall beemitted thereby. By thus'making the diaphragm of greater thickness atits center than at a point just within the rim 84, ll localize thefiexure of the disk, causing the same to occur wholly or almost whollyin a narrow annular zone just within the -clamped or peripheral edge ofthe disk, thus attaining the same substantial result that is attained bythe construction set forth in Figs. 1 to 6 inclusive. Under bothconstructions, the fiexure of the v or rendered so slight as to benegligible.

The rim 84 may be separated from direct engagement .with a ring 86, by aring of yielding material 88, such as felt or the like. The ring 86 isfitted on its external periphery with a ring 90, of felt or othersuitable packing, and this in turn tightly fits the interior of aresonator tube 10. -The ring 86' is secured in place within the tube 10by screws 92, and is clamped to the rim 84 by'bolts 93. By thisconstruction the ring 86 is held from direct engagement with the tube10, and a substantially air-tight end is provided for the resonatortube.

An armature 94, in the form of a disk, is secured to the under or outerface of the disk 82 by a bolt 96, which passes through felt washers 97,98, 99, 100, and a plate 102, these parts being all clamped togethertightly, but direct contact between opposing metal" surfaces ispreferably prevented, as by the felt washers. The plate 102, which mayconveniently be of some heavy material, serves as a rid'er to load thediaphragm, and lower its normal itch. On the lower or outer side of thedlsk 82 and carried by the head 117 of the bolt 96, are radial .rods 118threaded to receive weights 114 and 116 and jam-nuts 120. These weightsserve to supplement that of the rider 102, and by reason member.

'ends of said members.

amount of this weight is previously known, but in other cases it isconvenient to have 102 in the form of an easily changeable A pair ofelectromagnets 52 is mounted upon a plate 106, with theirpoles inproximity to the armature disk 94, the positions of said poles beingregulated by means of screws 108, 109. The former are threaded through atruss bar 110, which may be held in place against the ring 86 by screwsor bolts 112, but is preferably cast integrally with said ring, and thescrews 108'engage the outer face of the plate 106, while the screw 109is threaded through'said plate. The electromagnets 52 are connected to asource ofcurrent and controlled in the manner set forth above.

lit will be understood, however, that the tapering diaphragm can beemployed with out the weights. By the use of theform of resonator shown,the length of pipe required is reduced very materiallyas compared withwhat would be p p As illustrated in Figs. 9 and 10, the sonorous body.comprises a stiff member 26, which may be made of aluminum or wood, andsecured to a sheet of flexible material 18 held by rings 20, 20 in amanner similar to that hereinbefore described, and constituting astiffened or reinforced diaphragm. An armature 38, preferably in theform of a disk of soft iron is; located under the-sheet 18. A bolt 130passes through the member 26, armature 38,, collar 132, and a pair ofclamping plates 134, 135. This bolt is arranged to clamp the plates.134, 135 against a pair of tension members 136, 137, and to clamp thevarious parts together to form a comparatively rigid structure. Thetension members 136, 137, may be a pair of parallel wire rods which passthrough ears 138 provided on the under side of the rin 20. A pair ofelectromagnets 52 may be a justabl mounted on a truss 58, as alreadyexplaine The operation ofthis form of the invention is substantially thesame as heretofore explained, the tension of the members 136, 137 beingadjusted by means of nuts on the required with a fully open The combineddiaphragm and resonator when equipped with electromagnetic means foreffecting yibration of the diaphragm, may constitute one sound-producingmember or element of a musical instrument, a number'of such elementsequal to the number of notes desired being of course em ployed. As theseare to take the place of other sonorous. bodies heretofore employed insimilar relations, the claims are directed to the combined. diaphragmvand resonator, with means for effecting vibration of the diaphragm,rather than ,to a complete musical instrument.

It will be. observed that in the circularbearin points which would tendto distort the b0 y of the diaphragm, or make initial lines of rupture,In this way the diaphragm is caused to move facewise, uniformlythroughout its area, with the minimum of wear upon the diaphragm.

A clear distinction is to be drawn between a mere-conical sound-Wavecollector or funnel on the one hand, and a resonator, properlyso-called, in which the relative dimensions or proportions are made withspecial reference to strengthening or reinforcing a particular'tone,note or sound, and to suppressing other or extraneous sounds.

I claim:

1. In combination with a tubular resonator, a diaphragm stretched acrossthe mouth of the resonator and secured at its outer edge thereto, saiddiaphragm being rigid with the exception of a narrow annular zone nearits circumference; intersecting bands extending diametrically across thediaphragm in proximity thereto and carried by the resonator; and aconnection between the central portion of the diaphragm and theintersectin bands, whereby the diaphragm and said bands are caused tovibrate in unison and as determined by the tension of the bands.

2. In combination with a tubular resonator and an annular supportapplied to the mouth or end thereof, a diaphragm applied to said supportand closing the mouth of the resonator, said diaphra having a rigidcentral portion and a re atively flexible circumferential zone;intersecting bands extending diametrically across and in proximity to,the diaphr means for longitudinally stressing sai bands; and posts orbridges extendin from the diaphragm to the stressed ban s, and servingto shorten the effective vibrational length of the bands.

3.'A sound-producing device comprising a tubular resonator; a dlaphragmsecured at its outer ed e to said resonator and comprising a flexiilesheet; a braced rigid disk closely joined to said sheet and extendingnearly to the circumference of the latter; a tensioned band extendingdiametrically across the diaphra connections between said tensioned banand the diaphragm; an armature carried by said diaphragm; and

an electromagnet supported in proximity to said armature and serving byattraction thereof to vibrate the diaphragm.

In testimony whereof I have signed my nametto this specification in thepresence of two subscribing witnesses.

CHARLES CIIUDZIKOWSKI.

Witnesses:

EDWARD S. Cnooxn'rr, FRANK H. HENRIKSEN,

